Sick of the generator and need some opinions

[Delta5]

I recently started researching solar systems, inverter and battery systems so I could eventually be competent to setup an RV trailer to do some off-grid camping. I love to off-grid camp, however DW hates the generator and so do I! I camp mainly in the Adirondacks in NY, where there is a lot of forest cover and little opportunity to get peak sun on panels. I have a Forest River Shamrock currently that we use, however, eventually we are going to upgrade something different in the near future.

My dilemma now I have to use and configure my current TT and i want to get enough battery power to off-grid in my current trailer for a week, without the generator running. What I would like to get is two 200ah lithium batteries, run in parallel to camp off-grid for 5-7 days without charging. I looked at the power draws of everything on my trailer and I believe I have figured correctly that if everything is running in the camper, with the exception of the AC and microwave, I would be using approximately 100 watts an hour or roughly 8.33 amps. If I run everything 24-7, I would be using 200 ah. Not likely because I have never run everything at the same time. I figure an average of 50-70ah per day is what I realistically draw. The camper is not really adaptable to build a solar array and inverter system, so until I get a new TT I would like to add two, 200ah lithium batteries, battery shut off, Victron 712 Shunt and a solar suit case array to my existing TT.

My questions are:
1. If I am paralleling my two batteries and they are lithium 200ah; and charge and discharge at 50amps or less, can I wire the batteries in parallel with 6 AWG, or should I use 4 AWG.
2. Same question as above, but what should the wire size be to the shunt and battery cutoff?
3. Where should I fuse this system and I presume a 50amp fuse?
4. This may seem an obvious question, but if I am using a solar array suitcase with PWM, where do I hook up the terminals to charge? I assume to one side of the shunt and the other to the positive side of the battery? Anything else I am not seeing here?

Sorry if these questions seem incredibly basic.

Dave

 

[seneysolar]

When questioning wire size, default to the larger size.

Are you adding an inverter??? Camper already have one? Size of inverter is important.

Be careful with the charge controllers that come on the solar suitcases, they are generally crap, and may not be compatible with lithium batts.

Fuses should be sized to protect the wiring. You can always go smaller than that to protect devices but never larger than the wiring will support. If youre thinking 50A now thats probably fine for the oem camper dc loads but you'll need larger for an inverter.

 

[Tomthumb62]

1. If I am paralleling my two batteries and they are lithium 200ah; and charge and discharge at 50amps or less, can I wire the batteries in parallel with 6 AWG, or should I use 4 AWG.

Assuming your battery BMS is rated for 100A max continuous discharge, I would wire for that instead of your expected usage. 4AWG. If 200A BMS, then use 1/0AWG.

You could certainly “get away” with 6AWG with your expected load. But I wouldn’t do it because if you ever upgrade to use an inverter you’re going to need to upgrade the wiring anyways.

 

[time2roll]

#6 is fine on the batteries. This is very common for mid range RVs and trailers. Should have a 60 amp fuse close to the battery such that both batteries go through one fuse.

The entire main battery loop needs to be #6. Battery to fuse to fuse panel. Same for the negative with #6 from the accessory ground bus to the frame frame to shunt and shunt to battery. Probably already set up this way.

Fuse within 12 to 18 inches of the battery positive.

Not always sure what suit case solar is but I recommend 200 watts as a start. Yes make the connection to B+ and to the RV side of the shunt so power goes through the shunt.

Start with a sunny campsite for a three day weekend so the crutch (generator) can be left at home. The plan is solid.

 

[Delta5]

Thanks for the replies! There will not be an inverter installed. There is really no room for one and I will focus on that option for my next TT. The batteries I am considering are the 12v 206ah SOK. The BPMS is 150 ah rated. I will incorporate your suggestions and look at a solar suitcase array with compatible PWM for lithium batteries.

 

[seneysolar]

Thanks for the replies! There will not be an inverter installed. There is really no room for one and I will focus on that option for my next TT. The batteries I am considering are the 12v 206ah SOK. The BPMS is 150 ah rated. I will incorporate your suggestions and look at a solar suitcase array with compatible PWM for lithium batteries.

Ahh ok, you mentioned an inverter in your original post and running a generator ---- batteries only will leave you without ac power. So whats left to run? Lights, water pump and furnace?
What kind of refrigerator do you have? Hopefully that can be ran on propane?

Assuming you were running the generator for just the battery charger then?. Most trailers have a pretty small built in charger which may not be compatible with the lithium either. Getting a bigger charger, you can still utilize a small suitcase generator to recover your batteries and charge faster/ shorter run.

 

[Delta5]

Ahh ok, you mentioned an inverter in your original post and running a generator ---- batteries only will leave you without ac power. So whats left to run? Lights, water pump and furnace?
What kind of refrigerator do you have? Hopefully that can be ran on propane?

You are correct, lights, furnace, water pump, vent fans, and propane refrigerator. I will get a lithium charger that I can hook up directly to my batteries without going through my converter.